1. Technical Field
The present invention relates to vibration reduction and dampening and more particularly to an apparatus for dampening vibration of rotating shafts.
2. Description of the Related Art
A damper reduces the amplitude of vibration of a system. The vibration can be torsional or orbital. In piston driven automotive applications a crankshaft will twist back and forth at a very high frequency while it is rotating in its proper motion. This motion can lead to unexplained engine noise and vibration. In the past torsional dampers have been employed to reduce this high frequency twisting vibration.
Conventional crankshaft dampers reduce the amplitude and frequency of crankshaft vibrations. Excessive vibrations of a crankshaft can cause the crankshaft to fail and in many cases break. In other cases, the reduction of vibration amplitudes can reduce the noise and discomfort that a driver or passenger feels or hears, and is not limited to steering wheels, windows and accessories.
Referring to FIG. 1, in conventional torsion vibration control devices, such as in a conventional crankshaft damper 4, which employs natural rubber to function as a shock absorber. These designs adhere or bond a rubber material 6 between two metal portions. The first metal portion includes a hub 7 which supports the shaft. Another metal portion 8 is used as inertia and can support a pulley for ancillary equipment.
In this configuration, torsional 3 and linear motions 5 of a shaft (placed in the hub 6) cause a shearing stress in the rubber material. These shearing stresses cause the rubber to tear or delaminate from the metal.
Modern conditions for crankshaft dampers include unusually high rotations per minute, extreme heat and ozone exposure all of which can further contribute to the degradation of the rubber. Under these conditions the rubber's life expectancy and performance are significantly reduced.
In addition, rubber products were most commonly employed in a shear capacity to dampen only torsional or twisting motion. Conventional crankshaft designs were not capable of adequately damping fore and aft or orbital motions of the crankshaft. Further, due to the material properties of rubber, response lag for dampening vibrations was often inadequate especially in these high performance applications.
Therefore, a need exists for a damper design that provides vibration control in all directions as well as faster response times and greater orbital flexibility. A further need exists for a damping system that provides longer life and better damping capabilities. A still further need exists for a damper which can easily be serviced such that the damper material can be changed without having to replace all the metal parts.